Multiplexed read out electronics implemented on LTCC substrate for PbS array

Infrared detector arrays are very useful for spectroscopy to realize grating spectrometers with the ability for parallel signal detection. The signals from the detector pixels are usually very weak, and they have to be amplified. Because of the large number of pixels, it is often necessary to multiplex the signals to reduce the number of signal lines out from the package. This work presents the preamplifier and multiplexer modules built on low temperature co-fired ceramic (LTCC) substrate. The LTCC material is suitable for hermetic packaging, which is often needed for PbS detectors in process applications. The capacitive cross coupling of the modules is measured from the modules. The modules are implemented into a package next to the PbS array and the nonlinearity and normalized detectivity of the system are measured. The measurements show that special concern is needed in layout design to avoid capacitive cross coupling. The measurements also show that multiplexing does not deteriorate the good detectivity of the PbS detector.